[PATCH, ARM] Fix handling of function arguments with excess alignment

[Richard Earnshaw <rearnsha at arm dot com>]

PR target/56979 is a bug where a parameter to a function has an
alignment that is larger than its natural alignment.  In this case this
causes the mid-end to generate a mode for the argument that is
incompatible with the registers that are assigned for it.  We then end
up creating invalid RTL and subsequently abort when the pattern cannot
emit assembly code.

The fix is to decompose the assignment when this would happen in the
same way that we handle other block mode arguments and handle each piece
in turn.

	PR target/56979
	* arm.c (aapcs_vfp_allocate): Decompose the argument if the
	suggested mode for the assignment isn't compatible with the
	registers required.

Committed to trunk.

R.

Attachment: unaligned-arg.patch
Description: Text document